I put a summit proportioning valve on mine ( same as wilwood). Worked good once you get it tuned in right. Nice being able to adjust it. Only problem i had was the nob seized up so i ended up turning the nob off. My advice is to keep the nob well lubed.
Heres a link with a guy that did it to a 4runner.
http://home.4x4wire.com/erik/4runner/brakes/
Check that everything works together first, i didnot witch lead to alot of trips to napa. I also did the chevy master cylinder and used a dual diafram booster out of a 94 4x4 toyota truck. All made a preatty big difference. Any ?'s about the swap just ask.